Author Topic: Bf109 vs Fw190 speed at low level (Read 4835 times)

GRUNHERZ · « **Reply #90 on:** October 13, 2004, 08:55:17 PM »

Yes lets move on.

Yes, the Mk108 hurt performace in all aspects, speed, climb and turn. I pointed that out as to why I thgught the 568km'h was a remarkable figure for a 109G14 MW50 with the heavier cannon. A lighter MG151 armed one might even be a few km/h faster.

I belive that you are reffering to Mietusch's report between 109 and 190 in JG26 joint operations. I always took the speed differential statement to be cruising speed, where the 109 is indeed poor. And of course if the Bf109G6s dont have MW50 then Fw190 is faster at low level, but that was never in doubt.

As for the timelines since there is no definite I think we can disagree.

BTW how are you going to organize your book? The Hermann Fw190A book is mess, dont do it like that...

Crumpp · « **Reply #91 on:** October 13, 2004, 09:51:27 PM »

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BTW how are you going to organize your book? The Hermann Fw190A book is mess, dont do it like that...

I agree. He also IMO does a poor job of covering later versions but he does cover the earlier versions well. I especially like Heinrich Beauvais input.

I plan on concentrating on the later versions of the FW-190A. From the FW-190A5 on up to the A9.

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You claim to have data shoeing a 575km/h or 585km/h Fw190A8 data, are these the planes stripped of guns anf fuel tans, and flying on half fuel to reach these speeds like Meyer pointed out?

No. Meyer did not have the correct drag for the FW-190A. The A/C appears to be minus the 115 liter Aux tank and outboard MG151's.

BTW You asked about the Dora that does 399mph on the deck:

It's the C3 fuel "Take off and emergency" rating line.

I gotta go. Tommorrow I will give you some pointers on getting your hands on original documentation if you are still interested.

Crumpp

Meyer · « **Reply #92 on:** October 13, 2004, 10:07:53 PM »

About the gap in performance between the U4 versions and the "default" versions of the 109... can only 10/13kg do a noticeable difference? At least that is what i got from calculating the weight of the Mk108/65 rounds vs MG151/200rounds

http://www.quarry.nildram.co.uk/WW2guneffect.htm

What do you think guys?

GRUNHERZ · « **Reply #93 on:** October 13, 2004, 10:14:37 PM »

I wondered about that too Meyer but the JG26 pilots said they noticed some difference.

Crummp how common were those 399mph doras?

Crumpp · « **Reply #94 on:** October 13, 2004, 10:36:37 PM »

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About the gap in performance between the U4 versions and the "default" versions of the 109... can only 10/13kg do a noticeable difference? At least that is what i got from calculating the weight of the Mk108/65 rounds vs MG151/200rounds

I wondered that myself. Seems rather large for such a small weight increase. I think it must have added drag from the larger hole or maybe it effected the CG?

It certainly did effect the performance though as can be seen from the data sheet and the pilot testimony. Why is kind of mystery.

I also know the weight increase from the 115 liter aux tank has a large impact on the FW-190A8's performance. It was only 40kg dry and 120kg when full. Another point is the USN FW-190A5 test's. The USN took a crash landed ground attack version and tried to reconvert it to a fighter version. They ballasted the weight to match. Frankly, the performance they got is pretty poor compared to the Focke-Wulf and Rechlin test's. Most of that is the engine and control surface adjustment I suspect. Some of it I believe can be attributed to the weight set up as well.

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Crummp how common were those 399mph doras?

Not really sure. The Dora is not my area, really. IIRC, the Luftwaffe very late in the war ran into a shortage of C3 fuel. I know all fuel was in short supply but C3 especially. It was reserved for Focke-Wulfs only. I assume that means Doras in 1945.

As you can see from the chart though, this set up is optimized for lower altitude performance.

Crumpp

GRUNHERZ · « **Reply #95 on:** October 13, 2004, 10:53:12 PM »

I dont know what the performance loss was with the MK108, I doubt it was much but just enough to be noticable. And intrestingly enough you can feel it in AH as well..

BTW Crummp which data sheet are yiu refering to for the performance loss figures with MK108?

If you are looking at the two G14 models and K4 sheet it doesnt show a loss. Look closely, the 560km/h SL figure is for the G14ASM high altitude optimized AS variant which is armed "wie G-6" prolly meaning standard MG151 armament only. The other G14 is the G14-U4 (DB605AM) with MW50 and armed "wie G-6/U4" meaning it has the performance degrading MK108 armament - this model makes the 568km/h at SL, but is slower at high alt.

Might be just a CG thing, but I'm kinda doubtful about the potential impact as the guns and ammo are allready mounted pretty close to CG anyway.

There wasnt any extra bigger hole for the gun tube in the spinner, it was pretty much the same size through the whole 109 G and K series..

The only external differences were IIRC a small gun gas vent on the lower right cowl, a new hatch for the gun's air supply filling connection, and possibly a spent case discharge port on the bottom. Though I'm aware of some debate whether the last item was actually fitted to the G models with MK108, but it certainly was to the K4.

So its a mystery exactly what the performance loss is or why, except that it prolly has to do with the MK108s extra weight more than other factors.

Angus · « **Reply #96 on:** October 14, 2004, 10:27:00 AM »

Ahhh, I see lots of charts, lots of info and some smileys

Will collect some charts from theses threads if you don't mind, and I'll try to clean up the graphics a bit.
Anyway, continue, gentlemen

Regards

Angus

Wotan · « **Reply #97 on:** October 14, 2004, 10:57:46 AM »

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Out of curiousity do you know about how many Mk 108's were produced?

I don't have an idea on the exact number produced but from what I have read it was only WNF that produced the G-14 with a 3cm cannon. I do know that the G-14s that the Hungarians flew had the 3 cm cannon, but they had bomb racks as well.

As pointed out the 3 cm cannon did not add much weight. I find it hard to believe it added enough to effect performance, unless the larger barrel created more drag or something.

The numbers I have for a 109G-14/U3 is 568 km/h @ SL (with MW-50 @ 1.70 ata).

The 109G6/U3 designation is sort of confusing. If you go to this site:

http://www.ww2.dk./air/recon.html

Tthen select one of the Nahaufklärungsgruppe (Close recce group).

For example I selected NAGr. 5 then scrolled to the bottom and clicked on Flugzeugbestand und Bewegungsmeldungen, 1./NAGr.5

Scroll down till you see 109G6/U3 listed. First shows up in Feb '44. But clearly the close recce groups wouldn't be flying a fighter variant. My point here is the G6/U3 and G6/R2 get confused.

The quote I provided above states that the G-14 is the new official name of the

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G-6 / MW-50 designation which was used internally by Mtt for G-6 equipped with the MW-50 system previously used on the recce G-6/R2 variant

So I would say that the only G-6 with MW-50 was a recce variant and it appeared in Feb '44 and the new G-6 + MW-50 fighter variant designated G-14 arrived in June '44.

butch2k · « **Reply #98 on:** October 14, 2004, 01:43:42 PM »

Beginning in April 1944 the G-6/U2 were transformed on the production line for MW-50 use rather than GM-1 moreover 200 kits were issued to transform the existing GM-1 using G-6/U2.
THe aircraft transformed on the production line were issued the light tank similar to the later G-14, but the modified G-6/U2 kept their the heavy GM-1 tank.

HoHun · « **Reply #99 on:** October 14, 2004, 04:56:52 PM »

Hi Grünherz,

>I dont know where yiou get the 560km/h figure or why you think the lighter MG151/20 armament would reduce the pergormance from 568km/h with the heavy MK108 to only 560km'h withn the lighter MG151/20 mounting.

Note that the 20-mm-armed Me 109G-14 achieves 560 km/h with a DB605ASM high-altitude engine, while the 30 mm Me 109G-14/U4 features the DB605AM.

Note that similar powers are given for both engines at sea level, but I think it's a bit doubtful this is correct since the larger AS-type supercharger would have eaten a bit more power than the standard one.

By the way, would you happen to have a higher resolution version of the two charts you referred to?

http://www.onpoi.net/ah/pics/users/587_1097703364_bf109g14data.jpg

http://www.onpoi.net/ah/pics/users/587_1097702425_fw190speeds.jpg

This looks like very good stuff :-)

Regards,

Henning (HoHun)

Meyer · « **Reply #100 on:** October 14, 2004, 05:21:22 PM »

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Originally posted by HoHun

Note that the 20-mm-armed Me 109G-14 achieves 560 km/h with a DB605ASM high-altitude engine, while the 30 mm Me 109G-14/U4 features the DB605AM.

Note that similar powers are given for both engines at sea level, but I think it's a bit doubtful this is correct since the larger AS-type supercharger would have eaten a bit more power than the standard one.

I don't know about that, but one thing is sure, both are different aerodynamically.

HoHun · « **Reply #101 on:** October 14, 2004, 05:38:14 PM »

Hi Meyer,

>I don't know about that, but one thing is sure, both are different aerodynamically.

In which regard?

Henning (HoHun)

Crumpp · « **Reply #102 on:** October 14, 2004, 05:48:20 PM »

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By the way, would you happen to have a higher resolution version of the two charts you referred to?

I believe I provided those charts. I can scan them to higher resolution if you wish.

I will do so and repost them.

Crumpp

GRUNHERZ · « **Reply #103 on:** October 14, 2004, 05:56:06 PM »

Yea HoHun I noticed that since the initial post and have mentioned that as a popssibole source of confusion in later posts.

Meyer · « **Reply #104 on:** October 14, 2004, 05:57:51 PM »

@Hohun: The cover of the engine, the G-14 with the AM engine have the bulges for the MG131 (just like the G-6), and the G-14/AS have the bigger cover just like the G-10 or K-4.

G-14:

G-14/AS:

I'm not sure if "cover" is the right word, my english is terrible